Method of and apparatus for forming electric terminals



Feb. 26, 1957 G. J. BuRNosKY `2,783,442

METHOD OF AND APPARATUS FOR FORMING ELECTRIC TERMINALS Filed Aug. 3, 1953 n.3.

Illia-7 rqTTO RNEY METHOD F AND APPARATUS FOR FORMING ELECTRlC TERMINALS George J. Burnosky, Colonia, N. J., assignor to The Thomas & Betts Co., Elizabeth, N. J., a corporation of New Jersey Application August 3, 1953, Serial No. 371,910 1 Claim. (Cl. 339-96) The invention relates in general to an improved technique in the art of permanently securing preformed sheet metal terminals, connectors and other electric fittings to the strand wire conductive core of a shielded cable without stripping back the insulation on the cable. The invention also relates to die cutting apparatus for practicing the method herein featured and to the end product produced thereby.

The primary object of the invention is to provide an extremely simplified technique in making a mechanical and electrical connection between `a conventional and preformed type of electric conductive metal barrel-forming part of a fitting and the core of a cable, even though the cable be for its entire length shielded, and thus with its strands held from fraying, in an insulation jacket, and to attain this without any preliminary treatment or modification of either the terminal or the shielded cable.

Broadly, I attain this objective, first, by inserting an end of a cable more or less casually into the barrel-element of a fitting, and, second, by utilizing a single-stroke crimping die operation on the barrel to attain, in succession, a two-slit cutting through the barrel to form a pointed prong from the material of the barrel; the bodily Vbending of the prong inwardly about an integral hinge connection with the barrel to cause the prong as it is being cut and so bent inwardly to itself provide a cutter operative in turn to cut sharply through the insulation on the cable in the part thereof in the paths of the cutting edges of the prong, to displace the insulation s0 cut into an out-of-the-way position within the strands; and, finally, to bury the pointed end of the prong within the strands forming the core of the cable, and in this way provide a permanently fared electric connection between the barrel and the core of the cable as an incident of a single punching operation.

Still another object of the invention is to provide a form of interconnecting electric interlock between the barrel and the cable operative to defeatsubsequent possibilities of the tting and cable separating in an axial direction.

Various other objects and advantages of the invention will be in part obvious from an inspection of the accompanying drawings and in part will be more fully set forth in the following particular description of one method for practicing the invention and one form of insulation piercing tool for practicing the method, and the invention also consists in certain new and novel features of construction and combination of parts hereinafter set forth and claimed.

In the accompanying drawing,

Fig. 1 is a view in axial section of two conventional and Well known stock parts, i. e., a terminal with the end of a shielded cable inserted in its bore and illustrating the rst, preparatory or assembling step of the method herein disclosed. l

Fig. 2 is a transverse sectional View taken on the line 2-2 of Fig. l;

Fig. 3 is an axial sectional view of the stock parts of f. K l CC Fig. 1 pierced with a double wedge form of indentor and illustrating the start of the next or operative step of the method;

Fig. 4 is an axial sectional view of the finished connection corresponding to Fig. 3 after the indentors have been advanced to the limit of their piercing movements, with the die removed and showing the relation of the parts at the termination of the crimping step;

Fig. 5 is a transverse sectional view taken on the line 5-5 of Fig. 4 and showing one of the fastening prongs in elevation;

Fig. 6 is a plan view of the finished connection, looking down on the showing in Fig. 4;

Fig. 7 is an end view of the coacting die elements of the piercing tool used in forming the above connection;

Fig. 8 is a plan view of the indentor die, looking upwardly from its work face as viewed in Fig. 7;

Fig. 9 is a transverse sectional view of the indentor die taken on the line 9-9 of Fig. 8;

Fig. l0 is a plan view of a` slightly modified form of the connection featuring a single insulation cutting prong; and

Fig. 11 is a sectional view taken on the iline 11-11 of Fig. l0.

In the drawings and referring first to Fig. l, there is shown a conventional connector 10 including a sheet metal barrel 11 and an apertured tang 12. In the instant case the barrel is formed of thin sheet copper which has been rolled to form the barrel as a cylinder, as is known in this art. Slidably fitted in the barrel is one end of a shielded cable 143. The cable is of convention-A al form and comprises a'wire conductive core 14 enclosed in a jacket 15 of insulating material. In the cases illustrated the core is of the multiple strand type and is formed of a plurality of copper wire strands. As illustrated the insulation forming the jacket is of a rubberlike material easy to cut therethrough, but the invention may be practiced on other forms of cable provided, for instance, with insulation of the fabric type.

In assembling the component parts it is simply necessary to slip an end of the cable with its insulation in tact thereon into the bore of the barrel and usually the frictional engagement of the cable in the barrel bore is sullicient to hold the parts together, at least temporarily until they can be fastened together as herein described. The assembly of barrel and cable is then inserted between the dies of a suitable punching tool or machine. For the requisite parts of such a machine used in forming the illustrated form of connection reference is had to Figs. 7-9.

In Fig. 7 there is shown the steel die elements of a pliers-like, manually operated tool or the die elements of a power actuated press, depending upon the size and material of the barrel to be operated upon as herein featured.

The die elements comprise a nest die 16 and an indentor die 17, mounted for relative movement to and from each other along a thrust line t-1. The work faces of the dies are each provided with a half cylinder recess in opposing relation to each other and coacting to provide a cylindrical recess 18, dimensioned to accommodate the barrel 11 in position to be operated upon as herein featured.

In the case illustrated the indentor dies are provided with two integral distinct and longitudinally spaced-apart wedges or piercing spikes 19 and 20. This is the preferred structure, but it is within the scope of the disclosure to provide the indentor die with only a single wedge or spike as suggested in forming the single prong of Figs. 10 and 11. Each wedge is in the form of a three-sided pyramid projecting from a stop face 21 formed by a at cylindrical extension 22 integral with the balance of the die to ,1imit, ,the 4extenhof penetratiomofihe associated wedge into and through therbarrel and the cable insulation. One of the wedge faces 23 extends parallel to the line of thrust `and-,the .other twoaces.24ffand-25rextend fromrthepoint 26 of-itsiwedge ,at sharp anglesftoreach other and to the face 23. The faces 24 and 25 areV each slightlytconcavelengthwise,v as .indicated by the dotted lines 27 in 1"ig..7, to form, the edgesbeveled. Thefinclined cutting edges of the faces 24 and 25 are sharp-,to provide a clean cutthrough the copper barrel.

As the two dies approach each other towards the position vshown in Fig. 3, the point 26-.irst engages the outer side of the barrel, squeezesthel same between the two dies and starts to penetrate the barrel with apoint penetration. With increase-indepth,ofpenetration the two downwardly facingninclinedaedges ofthe sides 24 and 25 of the indentor `begin to cuttwo. intersecting slits 28 and 2.9 (seeFig. 6) throughthe Vbarrel with thematerial between the slits forming a pointed prong 30 with its third uncut side 31 forminga hinge connection between the prong and the barrel. As the prong is bent inwardly its sharp edges 32 and 33 cut through the por-V tion of the .insulation in their paths and this, in turn, cuts through the insulation and forms the portion between the cuts into a triangular-shaped ap or apron 34. The prong30 is turned down over an arc of about 45 degrees and bears down on the apron to move it into an outof the-.way position in Whichitl is held by the rigidity of the bent prong.

The pointed end 35 of the prong works its way downwardly between the strands ofthe cable, separating the same, until a material portionof the prongis embedded in the core of the cable and inintimate .electricalvcontact therewith along its edges and at least the. portionof its dat under side not covered by theinsulation forming the apron is in electric contact with the cable core. The connection is then complete.

This leaves a triangular-shaped space 36 in the barrel from which the prong `has been cut and therebelow a.

space 38in the cable and into, or rather towards, this space 38,the strands Whichescapeon opposite sidesv of the prong 30 tend to distend, thus assisting the locking of the core 14 into such space or spaces.

While the disclosure as thus far described features .the use of only one wedge or piercing spike, the duplicate arrangement herein disclosed is of advantage overA the single lock in that the forty-live degree inclination of the prongs in relatively opposite directions insures a resistance operative to defeat possibility that `the cable may separate from the barrel'. As. by .reference to Fig 4, itis seen that a vpull on theV cable to the right as indicatedby the long upper arrow would be resisted by theV angularly disposed left prong being forced even further into .the conductors. Similarly, a pull Von the barrel to the left as indicated by the lo'wer longarrow would be resisted by the. right. prong biting further into the conductors than is shown.

In the more simplified showing in Figs. l0 and l1, only one of the above-described prongs is disclosed and in the place of the other prong there is shown a semispherical button 37 die-pressed from the barrel and indenting the insulation therewith, as shown at 39, in this case Without cutting the same. This button form of interlock has been found to be useful in additionally locking the cable and barrel in a crimped relation.

thus securing .the cable and connector by a fastening means which did not exist as such in the original stock parts, but is formed therefrom as an incident of the usual crimpingoperation, it is possible to lock the parts permanently togctherwithout necessity of providing for any special fasteners in the original stock. It is simply necessary to insert any suitable cable in the barrel and by means of ,a singlestroke of a piercing spike the parts are secu rely ylocked together.

I claim:

An electric connection formed of a plurality of preformed parts, one oft-said parts comprising a sheet metal terminal'connector having a dat, apertured tongue portion and a wire barrel portion coextensive therewith, said other part comprising an insulated cable having a core of conductor strandsftcompacted in a jacket'of insulating material, said wire barrel having a portion thereof struck out of its annular wall to provide a V-shape prong integrally connected mechanically and electrically to said wire barrel, said prong beingbent inwardly through said insulating jacketv and extending therebeyond into said core of conductor strands. to form' an electric current.

path betweenrthe core of said cable and said terminal connector, said wire barrel 'being further provided'adjacent the base of said prong with a conical indent forming a button-like depression extending inwardly into and below .theperiphery of said insulating jacket to pro videxan interlock between said wire barrel and insulating jacket. supplementing the interlock` between said wire barrel and said insulated cable formed by said prong.

ReferencesiCited'in the le of this patent UNiTED STATES PATENTS 

